Prior art still image and movie cameras memorialized image data on media (e.g., film or magnetic tape), but did not include provision to store other useful information.
Some years ago, still-image cameras with the capability to insert visible date text in a corner of the image frame became available, solving the problem of trying to recall the dates that photos of interest were taken.
More recently, the Advanced Photo System provided a magnetic encoding medium on the back of photographic film, permitting additional information to be stored (e.g., exposure information, whether flash was used, desired print size, etc.).
With the growing popularity of digital storage of image data, it would be helpful if auxiliary data could be stored in association with a photo. Such storage is now possible in the header fields of certain popular data formats, but such data can be lost if the file is converted to another format.
In one embodiment of the invention, auxiliary data about an image is steganographically encoded (“watermarked”) within the image itself. By integrating the image and the associated data in this fashion, the auxiliary data cannot become separated from the image. A great number of useful systems are thereby reliably enabled.
In another embodiment, a reference to auxiliary data is steganographically encoded within the image. The auxiliary data is stored in a metadata database that maps the reference encoded in an image to its corresponding metadata. Various imaging application programs and devices can access the metadata by extracting the reference from an image, and querying the database for metadata corresponding to the reference. The metadata database may be implemented in a network server to make metadata readily available to devices and applications distributed throughout a computer network.
The steganographic link may be used to retrieve image metadata across imaging systems. In one configuration, for example, imaging systems have metadata servers that maintain metadata for a collection of images. The metadata server is responsible for responding to requests for metadata associated with images in its collection. In the event that a metadata server does not have metadata associated with a particular image, it forwards the reference extracted from the image to a metadata router, which in turn, re-directs the request to the appropriate metadata server.
The steganographic data may be embedded in an image within an image capture device, or elsewhere. In one embodiment, the steganographic data is embedded in the image as part of the process of uploading it from the camera. In another embodiment, an image capture device embeds steganographic data in the image before uploading it to an external device.
The foregoing and additional features and advantages will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.